DOES AZATHIOPRINE DECREASE PERCENT REACTIVE ANTIBODIES IN PRE TRANSPLANT PATIENTS?

Abstract

P12 Aims: Elevated percent reactive antibodies (PRA) are associated with a poor outcome after renal transplantation and frequently prevent patients from receiving a transplant because of their association with a positive lymphocytic crossmatch (LXM). One of our patients, after having lost her first kidney transplant, presented elevated PRA and began taking azathioprine (AZ) on her own. Her PRA fell to undetectable levels, and she still has the second kidney we transplanted 6 years ago, with good function. This prompted us to study AZ as a possible PRA-lowering agent. Methods: A preliminary review was performed on patients with high PRA who had been placed on low dose AZ (50mg daily). Monthly blood samples were taken for PRA titers, hemogram and liver profile.. All patients with high PRA that were either on our waiting list or who had already been transplanted were included as controls. Statistical analysis using STAT200® software included t-test and contingency table analysis. Results: A total of 155 patients (60 male, 95 female) met the above criteria. Ninety-three patients are still in the transplant waiting list: 11 are on AZ and 82 are not. The other 62 were transplanted: 5 had been on AZ while the remaining 57 had not. Analysis of all cases showed that low dose AZ significantly lowered PRA levels (AZ: 5/16 (31.3%) vs No AZ: 9/139 (6.5%); X2 p<0.0001). Analysis of only transplanted patients, showed that AZ significantly lowered PRA (AZ: 3/5 (60%) vs No AZ: 3/57 (9%); p<0.019, Fisher), while the group awaiting transplantation showed no difference (AZ: 2/11 (18%) vs No AZ: 6/82 (7%); p=0.936, Fisher). Fifty seven patients transplanted without AZ versus 5 patients on AZ showed that they were transplanted with similar frequency (AZ: 5/16 (31.3%) vs No AZ: 57/139 (41%); X2 p=0.798). Although total waiting time was comparable (AZ: 38.4 mo., No AZ: 30.8 mo., t-test, p=0.76), the transplantation time after starting AZ was shorter (8.2 mo., X2 p=0.005, t-test p=0.06). Patient and graft survival at 6 mo. was 100% in the AZ and 97.4% and 97.3% in the No AZ group (p=0.884, Fisher). HLA mismatches (>3) were more frequent in the AZ group but this was not significant (p=0.321, Fisher). Hemoglobin levels in the experimental group were lower after onset of the AZ treatment (t-test p=0.354). One additional patient in whom AZ did not lower PRA, had a negative LXM to a previously positive donor while on AZ therapy. Conclusions: This preliminary study showed that low dose azathioprine significantly lowers PRA levels and may decrease waiting time to transplantation in high PRA patients. To prevent or detect complications, hemogram and liver function should be monitored. A prospective study is underway.